In a control method of driving a motor, there is a technique of stopping a motor or maintaining the condition of the motor by igniting the motor with a rate set in advance, that is, a ratio of simultaneously igniting upper-side transistors of a power transistor that drives a motor for an emergency stop or a ratio of simultaneously igniting lower-side transistors of the power transistor (see, for example, Patent Literature 1).
Furthermore, there is a technique of preventing breakage of an inverter due to a regenerative voltage by causing line-to-line short-circuit between an inverter and a permanent magnet synchronous motor based on a regenerative voltage value generated when the permanent magnet synchronous motor is forcibly rotated (see, for example, Patent Literature 2).